[UX] Layouts: better visibility condition labels

[klonos]

...while filing a PR for #3033, I have noticed several inconsistencies with the labels of the visibility conditions. The screenshot below will give you an idea:

...so some conditions are wrapped in double quotes (which totally does not make sense when multiple conditions separated by commas), some are in italics, some are just normal unquoted non-italic text. Also, some use a semicolon for listing the conditions, while others don't.

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PR by @klonos: backdrop/backdrop#2265

[klonos]

...lets also please decide whether to have periods at the end of each summary item or not.

[klonos]

From the PR sandbox:

@klonos Are you able to fix the conflicts in the PR?

I just tested this in Backdrop (before trying to patch with your updates), and it already seems much better than it was when you first filed this issue. However there are still some things I can see that could be improved (likely by your PR):

• Full stops (or not)
• Variable in inverted commas (or not)
• 'Not' uppercase (or lowercase)
• Variable prefixed with colon (or just part of the text)

I also think the configure/remove links should either be a drop button or at least changed to be in the proper order, but I've filed a seperate issue for that: #4529